1. Field of the Invention
This invention generally relates to a bearing assembly and in particular to a crossed roller bearing assembly including a plurality of rollers arranged alternately in a crossed relationship.
2. Description of the Prior Art
A typical crossed roller bearing assembly is disclosed in the U.S. Pat. No. 3,275,391. An improved crossed roller bearing assembly is disclosed in the U.S. Pat. No. 4,606,654, which is assigned to the assignee of this application and which is hereby incorporated by reference. In the structure disclosed in this U.S. Pat. No. 4,606,654, an insertion hole for inserting a plurality of rollers into a space between a pair of inner and outer rings is provided in the outer ring and the insertion hole has a shape which is slightly larger than the diameter of the roller at its inlet and which gradually flares out toward the space between the inner and outer rings. In this structure, the outer ring can be made thinner without impairing its strength and structural integrity and the bearing assembly can be made smaller in size. However, in this structure, since a gap is defined between a plug inserted into the insertion hole after feeding a required number of rollers into the space between the outer and inner rings and the outer ring because of the flared out shape of the insertion hole, the guide surface of the outer ring along which the rollers roll is not smooth so that the rollers tend to strike against the tip end of the plug when they roll. In addition, since the insertion hole has a flared-out structure, difficulty is encountered in manufacture.